package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.SeckillVoucher;
import com.hmdp.entity.Voucher;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.SimpleRedisLock;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author junyong
 * @since 2024-8-6
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    IVoucherOrderService proxy;


    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    // 用于线程池处理的任务
    // 当初始化完毕后，就会去从消息队列中去拿信息
    private class VoucherOrderHandler implements Runnable {
        private String QUEUE_NAME = "stream.orders";
        @Override
        public void run() {
            while (true) {
                try {
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 >
                    List<MapRecord<String, Object, Object>> records = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(QUEUE_NAME, ReadOffset.lastConsumed())
                    );
                    // 2.判断订单消息是否为空
                    if(records == null || records.isEmpty()){
                        // 3. 如果为空,说明消息队列中无消息，无限循环
                        continue;
                    }
                    // 4.有消息处理消息
                    MapRecord<String, Object, Object> record = records.get(0);
                    Map<Object, Object> msg = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(msg, new VoucherOrder(), true);
                    // 5.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 6.ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(QUEUE_NAME, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 0
                    List<MapRecord<String, Object, Object>> records = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(QUEUE_NAME, ReadOffset.from("0"))
                    );
                    // 2.判断订单消息是否为空
                    if(records == null || records.isEmpty()){
                        // 3. 如果为空,说明消息队列中无消息，无限循环
                        break;
                    }
                    // 4.有消息处理消息
                    MapRecord<String, Object, Object> record = records.get(0);
                    Map<Object, Object> msg = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(msg, new VoucherOrder(), true);
                    // 5.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 6.ACK确认
                    stringRedisTemplate.opsForStream().acknowledge("s1", "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理pendingList异常", e);
                }
            }
        }

        private void handleVoucherOrder(VoucherOrder voucherOrder) {
            //1.获取用户
            Long userId = voucherOrder.getUserId();
            // 2.创建锁对象
            RLock redisLock = redissonClient.getLock("lock:order:" + userId);
            // 3.尝试获取锁
            boolean isLock = redisLock.tryLock();
            // 4.判断是否获得锁成功
            if (!isLock) {
                // 获取锁失败，直接返回失败或者重试
                log.error("不允许重复下单！");
                return;
            }
            try {
                //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy.createVoucherOrder(voucherOrder);
            } finally {
                // 释放锁
                redisLock.unlock();
            }
        }
    }


    @Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher seckillVoucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (seckillVoucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("秒杀还未开始");
        }
        // 3.判断秒杀是否结束
        if (seckillVoucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("秒杀已经结束");
        }
        // 4.调用lua脚本,完成秒杀资格判断(库存是否大于0以及是否满足一人一单)
        // 拿到用户信息
        Long userId = UserHolder.getUser().getId();
        // 拿到订单号信息
        long orderId = redisIdWorker.nextId("order");
        // 调用lua脚本
        Long res = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(), String.valueOf(orderId)
        );
        // 5.判断结果是否为0
        if (res != 0) {
            return Result.fail(res == 1 ? "库存不足!" : "重复下单!");
        }
        // 6.获取代理对象:用于调用事务方法
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 7. 返回订单id
        return Result.ok(orderId);
    }

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 5.一人一单
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();
        Integer count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        if (count > 0) {
            log.error("用户只能购买一次！");
        }
        // 6.扣减库存
        boolean success = seckillVoucherService.update().
                setSql("stock = stock - 1").
                eq("voucher_id", voucherId).
                gt("stock", 0).//eq("stock", seckillVoucher.getStock()).
                update();
        if (!success) {
            log.error("库存不足");
        }
        save(voucherOrder);
    }
}


